On a hill, near the village of Agios Matthaios, stand the remnants of the Gardiki castle, an octagonal Byzantine castle, with eight towers and three gates, built in the 13th century to protect the inhabitants of Zygonos, at that time. But neither they nor the village could be saved from the raid of Hayreddin Barbarossa, who plundered the entire island in the 16th century! (The village of Zygonos was rebuilt in the 16th century at a higher and more inaccessible place, under the name of Agios Mattheos!)